JP2023073782A - Electrochemical cell for water electrolysis, water electrolysis device, and water electrolysis method - Google Patents

Abstract

To provide an electrochemical cell for water electrolysis, comprising a face sealing material for sealing a cathode, whose sealing ability can be improved over the conventional one.SOLUTION: An electrochemical cell for water electrolysis comprises an electrolyte membrane, an anode disposed on one main surface of the electrolyte membrane, a cathode disposed on the other main surface of the electrolyte membrane, an anode separator disposed on the anode to comprise a first channel for the anodic fluid to flow therethrough, and a cathode separator disposed on the cathode to comprise a second channel for the cathodic fluid to flow therethrough, and applies a voltage between the anode and the cathode to generate oxygen at the anode and to generate hydrogen at the cathode. The electrochemical cell for water electrolysis comprises a surface sealing material disposed on the outer periphery of the region facing the cathode, of the cathode separator's cathode-side main surface, which surface sealing material is of a three-layered structure constituted by a metal sheet and a pair of elastic sheets each disposed on either main surface of the metal sheet.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to an electrochemical cell for water electrolysis, a water electrolysis device, and a water electrolysis method.

As a countermeasure against global warming, the use of renewable energy such as sunlight and wind power is attracting attention. However, when power obtained from renewable energy is supplied to appropriate power loads, there is a possibility that surplus power that is not used to supply power to the power loads may occur. Therefore, the utilization efficiency of renewable energy is not necessarily sufficient. Therefore, a method of storing surplus electric power as hydrogen energy by producing hydrogen using the surplus electric power is being studied.

Here, electrolysis of water is generally known as a method of producing hydrogen using electrical energy. Electrolysis of water is also called water electrolysis, and the development of highly efficient and long-life water electrolyzers has been studied in order to stably produce hydrogen at low cost in water electrolysis.

For example, in Patent Document 1, a water electrolysis apparatus in which oxygen is generated from the anode and hydrogen is generated from the cathode by applying a voltage between an anode and a cathode that are arranged with a diaphragm interposed therebetween. is proposed.

WO2021/015120

An object of the present disclosure is to provide, as an example, an electrochemical cell for water electrolysis, a water electrolysis device, and a water electrolysis method that can improve the sealing performance of a face seal material for sealing a cathode compared with conventional ones.

An electrochemical cell for water electrolysis according to one aspect of the present disclosure includes an electrolyte membrane, an anode provided on one main surface of the electrolyte membrane, and a cathode provided on the other main surface of the electrolyte membrane. an anode separator provided on the anode and having a first channel through which an anode fluid flows; and a cathode separator provided on the cathode and having a second channel through which a cathode fluid flows, wherein the anode and the In an electrochemical cell for water electrolysis in which oxygen is generated at the anode and hydrogen is generated at the cathode by applying a voltage between the cathode and the cathode, the main surface on the cathode side of the cathode separator faces the cathode A face seal material is provided on the perimeter of the region, said face seal material having a three-layer structure in which an elastic sheet is provided on each of both major surfaces of a metal sheet.

A water electrolysis apparatus according to one aspect of the present disclosure includes the water electrolysis electrochemical cell described above and a voltage applicator that applies a voltage between the anode and the cathode.

A water electrolysis method according to one aspect of the present disclosure includes an electrolyte membrane, an anode provided on one main surface of the electrolyte membrane, a cathode provided on the other main surface of the electrolyte membrane, and a cathode provided on the anode. an anode separator having a first channel through which an anode fluid flows; a cathode separator provided on the cathode and having a second channel through which a cathode fluid flows; and a face seal member provided on the outer periphery of the opposing regions, wherein the face seal member has a three-layer structure in which an elastic sheet is provided on each of both main surfaces of a metal sheet. In the cell water electrolysis method, a voltage is applied between the anode and the cathode to generate oxygen at the anode and hydrogen at the cathode.

The electrochemical cell for water electrolysis, the water electrolysis device, and the water electrolysis method according to one aspect of the present disclosure have the effect of improving the sealing performance of the face sealing material for sealing the cathode compared with the conventional one.

FIG. 1 is a diagram showing an example of the electrochemical cell for water electrolysis of the first embodiment. FIG. 2 is a diagram showing an example of the water electrolysis device of the first embodiment. FIG. 3 is a diagram showing an example of the electrochemical cell for water electrolysis of the second embodiment.

Patent Document 1 proposes a gasket for suppressing leakage of the electrolytic solution and electrolysis-generated gas from the electrolytic cell. was found not to have been adequately studied.

A gasket is pressed against the cathode-side metal frame with an appropriate fastening force in the periphery of the diaphragm in the electrolytic cell. Here, if the surface of the cathode-side metal frame in contact with the gasket is formed with flow channels for discharging unreacted electrolytic solution and hydrogen gas generated by electrolysis, the sealing performance of the gasket deteriorates. there is a possibility. This is for the following reasons.

Gaskets are generally constructed of an elastic material such as rubber, as described in US Pat. In this case, for example, when the members are fastened so as to press the gasket against the cathode-side metal frame, if uneven fastening force acts on the gasket, the gasket tends to be deformed so as to fall into the channel groove. As a result, the sealing performance of the gasket may deteriorate due to factors such as deformation or breakage of the gasket. Then, the electrolyte and hydrogen may leak to the outside. In other words, the present inventors found that the rigidity of the gasket was insufficient only with a rubber gasket for pressing against the cathode-side metal frame, and came up with the following aspect of the present disclosure.

That is, the electrochemical cell for water electrolysis of the first aspect of the present disclosure includes an electrolyte membrane, an anode provided on one main surface of the electrolyte membrane, a cathode provided on the other main surface of the electrolyte membrane, and an anode an anode separator overlying the anode separator and having a first flow path through which the anode fluid flows; and a cathode separator overlying the cathode and having a second flow path through which the cathode fluid flows; In an electrochemical cell for water electrolysis in which oxygen is generated at the anode and hydrogen is generated at the cathode by applying , a face seal provided on the outer periphery of the region facing the cathode of the cathode-side main surface of the cathode separator The face seal material has a three-layer structure in which an elastic sheet is provided on each of both major surfaces of a metal sheet.

According to such a configuration, the electrochemical cell for water electrolysis of this aspect can improve the sealing performance of the face sealing material for sealing the cathode as compared with the conventional one.

Specifically, in the electrochemical cell for water electrolysis of this aspect, the face seal material for sealing the cathode has a three-layer structure comprising a metal sheet and an elastic sheet provided on both main surfaces of the metal sheet. Therefore, the rigidity of the face seal material is improved as compared with the case where the face seal material is composed of a single elastic sheet. As a result, in the electrochemical cell for water electrolysis of this aspect, for example, when the members are fastened so as to press the face seal against the cathode separator, even if uneven fastening force acts on the face seal material, the face This suppresses the sealing material from falling into the second flow path. Therefore, in the electrochemical cell for water electrolysis of this aspect, the sealing performance of the face seal material deteriorates due to factors such as deformation or breakage of the face seal material, compared to the case where the face seal material is composed of a single elastic sheet. Since the possibility can be reduced, it becomes difficult for the cathode fluid containing hydrogen produced at the cathode to leak to the outside.

The electrochemical cell for water electrolysis of the second aspect of the present disclosure is the electrochemical cell for water electrolysis of the first aspect, wherein the face seal provided on the outer periphery of the region facing the anode of the anode-side main surface of the anode separator The face seal material may be a three-layer structure in which an elastic sheet is provided on each of both major surfaces of the metal sheet.

According to such a configuration, the electrochemical cell for water electrolysis of this aspect can improve the sealing performance of the face sealing material for sealing the anode as compared with the conventional one.

Specifically, in the electrochemical cell for water electrolysis of this embodiment, the face sealing material for sealing the anode has a three-layer structure comprising a metal sheet and elastic sheets provided on both main surfaces of the metal sheet. , the rigidity of the face seal material is improved as compared with the case where the face seal material is composed of a single elastic sheet. As a result, in the electrochemical cell for water electrolysis of this aspect, for example, when the members are fastened so as to press the face seal against the anode separator, even if uneven fastening force acts on the face seal material, the face This suppresses the sealing material from falling into the first flow path. Therefore, in the electrochemical cell for water electrolysis of this aspect, the sealing performance of the face seal material deteriorates due to factors such as deformation or breakage of the face seal material, compared to the case where the face seal material is composed of a single elastic sheet. Since the possibility can be reduced, the anode fluid containing oxygen produced by electrolysis is less likely to leak to the outside.

The electrochemical cell for water electrolysis of the third aspect of the present disclosure may be the electrochemical cell for water electrolysis of the first aspect or the second aspect, wherein the electrolyte membrane may be an anion exchange membrane.

In the electrochemical cell for water electrolysis of the fourth aspect of the present disclosure, in the electrochemical cell for water electrolysis of any one of the first to third aspects, the elastic sheet may be alkali-resistant.

When the anode fluid or cathode fluid is an aqueous solution containing alkali, it is appropriate to select an alkali-resistant material as the base material of the elastic sheet in the electrochemical cell for water electrolysis of this embodiment.

In the electrochemical cell for water electrolysis of the fifth aspect of the present disclosure, in the electrochemical cell for water electrolysis of any one of the first to fourth aspects, the metal sheet may be alkali-resistant.

When the anode fluid or cathode fluid is an aqueous solution containing alkali, it is appropriate to select an alkali-resistant material as the base material of the metal sheet in the electrochemical cell for water electrolysis of this embodiment.

A water electrolysis device according to a sixth aspect of the present disclosure may include an electrochemical cell for water electrolysis according to any one of the first aspect to the fifth aspect, and a voltage applicator that applies a voltage between the anode and the cathode. .

The effects of the water electrolysis device of this aspect are the same as the effects of the electrochemical cells for water electrolysis of the above-described aspects, and thus description thereof is omitted.

A water electrolysis method of a seventh aspect of the present disclosure includes an electrolyte membrane, an anode provided on one main surface of the electrolyte membrane, a cathode provided on the other main surface of the electrolyte membrane, and provided on the anode, an anode separator having a first channel through which an anode fluid flows; a cathode separator provided on the cathode and having a second channel through which a cathode fluid flows; and a face seal member provided on the outer circumference, wherein the face seal member has a three-layer structure in which an elastic sheet is provided on each of both main surfaces of a metal sheet. , oxygen is generated at the anode and hydrogen is generated at the cathode by applying a voltage between the anode and the cathode.

The effects of the water electrolysis method of this aspect are the same as the effects of the electrochemical cell for water electrolysis of the first aspect, and thus the description thereof is omitted.

Embodiments of the present disclosure will be described below with reference to the accompanying drawings. It should be noted that each of the embodiments described below is an example of each of the aspects described above. Therefore, the shapes, materials, components, and arrangement positions and connection forms of the components shown below are merely examples, and do not limit each of the above aspects unless stated in the claims. . In addition, among the following constituent elements, constituent elements that are not described in independent claims representing the top concept of each of the above aspects will be described as optional constituent elements. Further, in the drawings, the description of the components with the same reference numerals may be omitted. The drawings schematically show each component for easy understanding, and the shape and dimensional ratio may not be exact representations.

(First embodiment)
[Overall configuration of device]
FIG. 1 is a diagram showing an example of the electrochemical cell for water electrolysis of the first embodiment.

In the example shown in FIG. 1, the electrochemical cell 10 for water electrolysis includes an electrolyte membrane 21, an anode AN, a cathode CA, a cathode separator 27, an anode separator 26, an insulating sheet 28, a face sealing material 41, and a face seal material 42 . In the electrochemical reaction area of the water electrolysis electrochemical cell 10, the electrolyte membrane 21, the anode catalyst layer 22, the cathode catalyst layer 23, the anode power feeder 24, the cathode power feeder 25, the anode separator 26 and the cathode separator 27 are laminated. ing.

By applying a voltage between the anode AN and the cathode CA, the electrochemical cell 10 for water electrolysis described above can generate oxygen at the anode AN and hydrogen at the cathode CA. will explain.

Anode AN is provided on one main surface of electrolyte membrane 21 . The anode AN is an electrode that includes an anode catalyst layer 22 and an anode power supply 24 . An annular face seal member 41 is provided so as to surround the anode AN in plan view. As a result, the anode AN is properly sealed with the face seal material 41 .

Cathode CA is provided on the other main surface of electrolyte membrane 21 . Cathode CA is an electrode including cathode catalyst layer 23 and cathode power supply 25 . In plan view, an annular face seal member 42 is provided so as to surround the cathode CA. Thereby, the cathode CA is properly sealed with the face seal material 42 .

The electrolyte membrane 21 may have any configuration as long as it is an electrolyte membrane having ion conductivity. For example, the electrolyte membrane 21 may be a proton exchange membrane or an anion exchange membrane.

Anode catalyst layer 22 comprises a catalyst metal and a carrier. The catalyst metal that can be used in the anode catalyst layer 22 is not limited to a specific type, but examples of electrode catalysts include platinum and iridium oxide. Incidentally, the catalyst metal is carried on a carrier such as carbon, nickel, or titanium, for example.

Cathode catalyst layer 23 comprises a catalyst metal and a carrier. The catalyst metal that can be used in the cathode catalyst layer 23 is not limited to a specific type, but examples of electrode catalysts include platinum. Incidentally, the catalyst metal is carried on a carrier such as carbon, nickel, or titanium, for example.

The anode power supply 24 is a member having electrical conductivity and diffusibility of the anode fluid. Specifically, as the anode fluid passes through the anode flow channel 31 , the anode fluid can diffuse to the anode catalyst layer 22 via the anode current feeder 24 . The anode fluid may be, for example, an aqueous solution containing alkali, but is not limited to this.

Here, the anode power supply 24 is composed of, for example, a porous sheet containing metal, carbon, or the like. When the anode power supply 24 is made of metal, examples of the metal material include, but are not limited to, titanium, stainless steel, and nickel. The porous sheet may be, for example, a non-woven fabric made of sintered particles or fibers, a mesh made of metal fiber fabric, or the like, but is not limited to these.

The cathode power supply 25 is a member having electrical conductivity and cathode fluid diffusibility. Specifically, as the cathode fluid passes through the cathode flow channel 32 , the cathode fluid can diffuse to the cathode catalyst layer 23 via the cathode current feeder 25 . As the cathode fluid, for example, an aqueous solution containing an alkali can be used, but it is not limited to this.

Here, the cathode power supply 25 is composed of, for example, a porous sheet containing metal, carbon, or the like. When the cathode power supply 25 is made of metal, metal materials include, but are not limited to, titanium, stainless steel, and nickel. The porous sheet may be, for example, a non-woven fabric made of sintered particles or fibers, a mesh made of metal fiber fabric, or the like, but is not limited to these.

As described above, the electrolyte membrane 21 is sandwiched between the anode AN and the cathode CA so as to be in contact with the anode catalyst layer 22 and the cathode catalyst layer 23, respectively. The stack of electrolyte membrane 21, anode AN and cathode CA is generally referred to as a membrane-electrode assembly (hereinafter MEA).

Note that, in a plan view of the MEA, the electrolyte membrane 21 extends so as to protrude from the MEA, and an annular insulating sheet 28 is provided so as to be in contact with the end of the extending portion of the electrolyte membrane 21 . This properly prevents an electrical short circuit between the anode AN and the cathode CA. Rubber or resin can be used as the material of the insulating sheet 28 . Examples thereof include silicone rubber, EPDM (ethylene propylene diene rubber), FKM (fluorinated rubber), PTFE (polytetrafluoroethylene), PP (polypropylene), and PS (polystyrene). When the anode fluid or cathode fluid is an aqueous solution containing alkali, it is appropriate to select an alkali-resistant material as the base material of the insulating sheet 28, and it is desirable to use EPDM, for example.

The anode separator 26 is a member provided on the anode AN and having an anode flow channel 31 through which an anode fluid flows. The anode separator 26 is composed of a member having electrical conductivity and gas barrier properties. Examples of materials for such members include metals and carbon. For example, when the anode separator 26 is made of metal, titanium, stainless steel, nickel, or the like can be used. In addition, in order to improve the conductivity of the anode separator 26, noble metal plating may be applied as appropriate. When the anode separator 26 is made of carbon, the anode separator 26 may be a sintered dense body of carbon or a formed body of carbon and resin.

The cathode separator 27 is a member provided on the cathode CA and having a cathode flow channel 32 through which a cathode fluid flows. The cathode separator 27 is composed of a member having electrical conductivity and gas barrier properties. Examples of materials for such members include metals and carbon. For example, when the cathode separator 27 is made of metal, titanium, stainless steel, nickel, or the like can be used. In addition, in order to improve the conductivity of the cathode separator 27, noble metal plating may be applied as appropriate. When the cathode separator 27 is made of carbon, the cathode separator 27 may be a sintered dense body of carbon or a formed body of carbon and resin.

As described above, the MEA is sandwiched between the anode separator 26 and the cathode separator 27 so as to be in contact with the main surface of the anode separator 26 on the anode side and the main surface of the cathode separator 27 on the cathode side.

[Configuration of Anode Channel and Cathode Channel]
An example of the configuration of the anode channel 31 and the cathode channel 32 will be described below.

The anode flow channel 31 is provided on the main surface of the anode separator 26 on the anode side, and is used to supply an anode fluid to the anode AN from the outside and to discharge the anode fluid and oxygen (gas produced by electrolysis) from the anode AN to the outside. flow path.

The anode channel 31 includes a first communication channel 31A, an electrode passage channel 31B, and a second communication channel 31C.

Here, although illustration is omitted, when the water electrolysis device 100 includes a stack in which a plurality of electrochemical cells 10 for water electrolysis are stacked, an anode supply manifold and an anode discharge manifold are provided at appropriate locations of the stack. may Each of the anode supply manifold and the anode exhaust manifold is constituted by a series of through-holes passing through each member of the stack in a direction parallel to the stacking direction of these members.

In each of the water electrolysis electrochemical cells 10, the anode supply manifold communicates with the first communication path 31A. In the example shown in FIG. 1, the first communication path 31A is composed of a first channel groove provided on the main surface of the anode separator 26, and the end of the first channel groove is connected to the anode supply manifold. , it extends linearly in the direction perpendicular to the plane of the paper. The extending direction of the first flow channel is not limited to this, and may be a direction other than that shown in FIG.

Further, in each of the water electrolysis electrochemical cells 10, the anode discharge manifold and the second communication path 31C are in communication. In the example shown in FIG. 1, the second communication path 31C is configured by a second channel groove provided on the main surface of the anode separator 26, and the end of the second channel groove is connected to the anode discharge manifold. It extends linearly in the direction perpendicular to the plane of the paper. However, the extending direction of the second flow channel is not limited to this, and may be a direction other than that shown in FIG.

Moreover, in each of the electrochemical cells 10 for water electrolysis, the electrode passage channel 31B communicates with the first communication channel 31A and the second communication channel 31C. In the example shown in FIG. 1, the electrode passage channel 31B is composed of a plurality of third channel grooves provided on the main surface of the anode separator 26, and both ends of the third channel grooves Although it extends linearly in a direction parallel to the paper so as to be connected to each of the first communication path 31A and the second communication path 31C, it is not limited to this. The third flow channel groove may be formed in a serpentine shape including a plurality of linear portions extending linearly in a direction parallel to the paper surface and a plurality of U-shaped folded portions.

As described above, in each of the water electrolysis electrochemical cells 10, when the anode fluid passes through the anode supply manifold from the outside, part of the anode fluid is supplied to the first communication path 31A. The anode fluid flowing through the first communication channel 31A is divided into each of the plurality of electrode passage channels 31B, and when passing through the electrode passage channels 31B, the anode fluid flows through the anode power feeder 24 to the anode catalyst layer. 22. As a result, an electrochemical reaction occurs in the anode catalyst layer 22 to generate oxygen. The mixed fluid of the anode fluid and oxygen that have passed through each of the electrode passage channels 31B merge in the second communication passage 31C, and the mixed fluid that has passed through the second communication passage 31C further merges in the anode discharge manifold. Finally, this mixed fluid is discharged outside from the anode discharge manifold.

In each of the water electrolysis electrochemical cells 10, suitable O-rings and O-ring grooves may be provided to prevent fluid leakage from the anode supply manifold and the anode exhaust manifold. Examples of O-ring materials include silicone rubber, EPDM (ethylene propylene diene rubber), FKM (fluorinated rubber), PTFE (polytetrafluoroethylene), PP (polypropylene), and PS (polystyrene). When the anode fluid is an aqueous solution containing alkali, it is appropriate to select an alkali-resistant material as the base material of the O-ring, and it is desirable to use EPDM, for example.

The cathode flow channel 32 is provided on the main surface of the cathode separator 27 on the cathode side, and serves to supply the cathode fluid to the cathode CA from the outside and to discharge the cathode fluid and hydrogen (electrolytically produced gas) from the cathode CA to the outside. flow path.

The cathode channel 32 includes a first communication channel 32A, an electrode passage channel 32B, and a second communication channel 32C.

Here, although illustration is omitted, when the water electrolysis device 100 includes a stack in which a plurality of electrochemical cells 10 for water electrolysis are stacked, a cathode supply manifold and a cathode discharge manifold are provided at appropriate locations of the stack. may The cathode supply manifold and the cathode exhaust manifold are each constituted by a series of through-holes passing through each member of the stack in a direction parallel to the stacking direction of these members.

In each of the water electrolysis electrochemical cells 10, the cathode supply manifold communicates with the first communication path 32A. In the example shown in FIG. 1, the first communication path 32A is composed of a first channel groove provided on the main surface of the cathode separator 27, and the end of the first channel groove is connected to the cathode supply manifold. , it extends linearly in the direction perpendicular to the plane of the paper. The extending direction of the first flow channel is not limited to this, and may be a direction other than that shown in FIG.

Also, in each of the water electrolysis electrochemical cells 10, the cathode discharge manifold and the second communication path 32C are in communication. In the example shown in FIG. 1, the second communication path 32C is composed of a second channel groove provided on the main surface of the cathode separator 27, and the end of the second channel groove is connected to the cathode discharge manifold. , it extends linearly in the direction perpendicular to the plane of the paper. However, the extending direction of the second flow channel is not limited to this, and may be a direction other than that shown in FIG.

Further, in each of the electrochemical cells 10 for water electrolysis, the electrode passage channel 32B communicates with the first communication channel 32A and the second communication channel 32C. In the example shown in FIG. 1, the electrode passage channel 32B is composed of a plurality of third channel grooves provided on the main surface of the cathode separator 27, and both ends of the third channel grooves Although it extends linearly in a direction parallel to the paper so as to be connected to each of the first communication path 32A and the second communication path 32C, it is not limited to this. The third flow channel groove may be formed in a serpentine shape including a plurality of linear portions extending linearly in a direction parallel to the paper surface and a plurality of U-shaped folded portions.

As described above, in each of the water electrolysis electrochemical cells 10, when the cathode fluid passes through the cathode supply manifold from the outside, part of the cathode fluid is supplied to the first communication path 32A. The cathode fluid flowing through the first communication channel 32A is split into each of the plurality of electrode passage channels 32B, and when passing through the electrode passage channels 32B, the cathode fluid flows through the cathode power feeder 25 to the cathode catalyst layer. 23. As a result, an electrochemical reaction that generates hydrogen occurs in the cathode catalyst layer 23 . The mixed fluid of the cathode fluid and hydrogen that have passed through each of the electrode passage channels 32B merge in the second communication passage 32C, and the mixed fluid that has passed through the second communication passage 32C further merges in the cathode discharge manifold. Finally, this mixed fluid is discharged outside from the cathode discharge manifold.

Appropriate O-rings and O-ring grooves may be provided in each of the water electrolysis electrochemical cells 10 to prevent fluid leakage from the cathode supply manifold and the cathode exhaust manifold. Examples of O-ring materials include silicone rubber, EPDM (ethylene propylene diene rubber), FKM (fluorinated rubber), PTFE (polytetrafluoroethylene), PP (polypropylene), and PS (polystyrene). When the cathode fluid is an aqueous solution containing alkali, it is appropriate to choose an alkali-resistant material as the base material for the O-ring, and it is desirable to use EPDM, for example.

The configuration of the anode channel 31 and the configuration of the cathode channel 32 described above are examples, and are not limited to this example.

For example, in the description above, the extending direction of the first communication path 31A and the second communication path 31C and the extending direction of the first communication path 32A and the second communication path 32C are the same direction perpendicular to the plane of the paper. may be shifted by 90°.

Further, the flow direction of the anode fluid in the first communication path 31A and the second communication path 31C and the flow direction of the cathode fluid in the first communication path 32A and the second communication path 32C may be the same direction, It may be in the opposite direction.

Furthermore, the electrode passage channel 31B and the electrode passage channel 32B may be composed of a large number of pores such as punching metal.

[Structure of face seal material]
An example of the configuration of the face seal material 41 and the face seal material 42 will be described below.

The face seal material 41 is provided on the outer circumference of the region facing the anode AN on the main surface of the anode separator 26 on the anode AN side. Specifically, the face seal material 41 is provided in an annular shape so as to surround the outer end of the MEA and cover the first communication path 31A and the second communication path 31C in plan view of the MEA. In addition, the face seal material 41 is sandwiched between the main surface of the anode separator 26 on the anode AN side and one main surface of the extending portion of the insulating sheet 28 and the electrolyte membrane 21 in the cross-sectional view of the MEA shown in FIG. ing.

The face seal material 41 is a member having insulating and sealing properties. Examples of materials for the face seal material 41 include silicone rubber, EPDM (ethylene propylene diene rubber), FKM (fluorinated rubber), PTFE (polytetrafluoroethylene), PP (polypropylene), and PS (polystyrene). can. When the anode fluid is an aqueous solution containing alkali, it is appropriate to select an alkali-resistant material as the base material of the face seal material 41, and it is desirable to use EPDM, for example.

The face seal material 42 is provided on the outer circumference of the region of the cathode CA side main surface of the cathode separator 27 facing the cathode CA. Specifically, the face seal material 42 is provided in an annular shape so as to surround the outer end portion of the MEA and cover the first communication path 32A and the second communication path 32C in plan view of the MEA. 1, the face seal material 42 is sandwiched between the main surface of the cathode separator 27 on the cathode CA side and the other main surface of the extending portion of the insulating sheet 28 and the electrolyte membrane 21. ing.

The face seal material 42 is a member having insulating and sealing properties. Specifically, the face seal material 42 has a three-layer structure in which elastic sheets 42B are provided on both main surfaces of a metal sheet 42A.

Examples of materials for the insulating elastic sheet 42B include silicone rubber, EPDM (ethylene propylene diene rubber), FKM (fluororubber), PTFE (polytetrafluoroethylene), PP (polypropylene), and PS (polystyrene). be able to. When the anode fluid is an aqueous solution containing alkali, it is appropriate to select an alkali-resistant material as the base material of the face seal material 41, and it is desirable to use EPDM, for example.

The metal sheet 42A is a member having higher rigidity than the elastic sheet 42B, and is made of a corrosion-resistant material. Examples of such materials include titanium, stainless steel, and nickel. Here, when the anode fluid contains an aqueous solution containing alkali, it is appropriate to select an alkali-resistant material as the base material of the metal sheet 42A, and it is desirable to use nickel, for example.

Also, the metal sheet 42A may be plated with a dissimilar metal. For example, if the metal sheet 42A is made of stainless steel, the stainless steel sheet may be plated with nickel or a noble metal. Here, when the anode fluid contains an aqueous solution containing alkali, it is appropriate to select an alkali-resistant material as the plating material, and it is desirable to use nickel, for example.

The sheet material forming the face seal material 42 may be fixed by an appropriate bonding method. This improves the ease of assembly of the electrochemical cell 10 for water electrolysis. Moreover, when the electrochemical cell 10 for water electrolysis is assembled, the electrolyte membrane 21 and the cathode power supply 25 are suppressed from being caught between the sheet members, and as a result, breakage of the sheet members can be suppressed. Examples of the bonding method include a method using an epoxy resin-based adhesive, and a vulcanization bonding method in which unvulcanized rubber and a metal sheet are vulcanized and bonded in a mold at the same time.

[motion]
An example of the operation of the electrochemical cell 10 for water electrolysis will be described below with reference to the drawings. The following operations may be performed, for example, by an arithmetic circuit (not shown) of the controller reading out the control program from the memory circuit of the controller. However, it is not essential that the controller perform the following operations. The operator may perform some of the operations. In the following example, the case where the operation is controlled by the controller will be described. Further, the operation of the water electrolysis electrochemical cell 10 in the case where the water electrolysis electrochemical cell 10 is an anion exchange membrane (AEM) cell and the anode fluid and the cathode fluid are aqueous potassium hydroxide solutions will be described below. explain.

First, an aqueous potassium hydroxide solution is supplied to each of the anode AN and the cathode CA of the electrochemical cell 10 for water electrolysis.

Next, when a voltage is applied between the anode AN and the cathode CA by a voltage applicator (not shown), the hydroxide ions are separated into oxygen and electrons by an oxidation reaction in the anode catalyst layer 22 (equation (1) ). Oxygen is discharged outside together with the aqueous potassium hydroxide solution, and electrons move to the cathode catalyst layer 23 through the voltage applicator. Hydrogen molecules and hydroxide ions are produced by a reduction reaction in the cathode catalyst layer 23, and the hydroxide ions conduct through the electrolyte membrane 21 (equation (2)).
Anode: 4OH ⁻ →O ₂ +2H ₂ O+4E ⁻ (1)
Cathode: 4H ₂ O+4E ⁻ →2H ₂ +4OH ⁻ (2)
By applying a voltage between the anode AN and the cathode CA in this manner, an electrochemical reaction is performed in which oxygen is generated at the anode AN and hydrogen is generated at the cathode CA.

Hydrogen produced at the cathode CA may be compressed using pressure control means such as a back pressure valve or a regulating valve provided in an appropriate pipe communicating with the cathode flow channel 32 . Thereby, high-pressure hydrogen can be generated at the cathode CA.

As described above, the electrochemical cell for water electrolysis 10 and the water electrolysis method of the present embodiment can improve the sealing performance of the face sealing material 42 for sealing the cathode CA compared with the conventional one.

Specifically, in the electrochemical cell 10 for water electrolysis, the face seal material 42 has a three-layer structure including a metal sheet 42A and an elastic sheet 42B provided on both main surfaces of the metal sheet 42A. The rigidity of the face seal material 42 is improved as compared with the case where the seal material 42 is composed of a single elastic sheet. As a result, in the electrochemical cell 10 for water electrolysis and the water electrolysis method of the present embodiment, for example, when the above members are fastened so as to press the face seal material 42 against the cathode separator 27, the face seal material 42 is uneven. Even if a strong fastening force acts, the face seal material 42 is prevented from falling into the first communication path 32A and the second communication path 32C. Therefore, in the electrochemical cell 10 for water electrolysis and the water electrolysis method of the present embodiment, compared to the case where the face seal material 42 is composed of a single elastic sheet, the face seal material 42 may be deformed or damaged due to factors such as deformation or breakage. Since the possibility that the sealing performance of the sealing member 42 is deteriorated can be reduced, the cathode fluid containing hydrogen produced at the cathode is less likely to leak to the outside.

(Example)
FIG. 2 is a diagram showing an example of a water electrolysis device of an example of the first embodiment.

In the example shown in FIG. 2 , the water electrolysis device 100 includes a water electrolysis electrochemical cell 10 and a voltage applicator 50 . Here, since the electrochemical cell 10 for water electrolysis is the same as that of the first embodiment, description thereof is omitted.

Voltage applicator 50 is a device that applies a voltage between anode AN and cathode CA. Voltage applicator 50 may have any configuration as long as it can apply a voltage between anode AN and cathode CA. In the example shown in FIG. 1, the high potential side terminal of the voltage applicator 50 is connected to the anode AN, and the low potential side terminal of the voltage applicator 50 is connected to the cathode CA. Examples of the voltage applicator 50 include a DC/DC converter and an AC/DC converter. A DC/DC converter is used when the voltage applicator 50 is connected to a DC power source such as a solar cell, a fuel cell, or a battery. An AC/DC converter is used when the voltage applicator 50 is connected to an AC power supply such as a commercial power supply. In addition, the voltage applicator 50, for example, applies a voltage between the anode AN and the cathode CA, and a It may also be a power source in which the current drawn is regulated. Thereby, in the electrochemical cell 10 for water electrolysis, by applying a voltage between the anode AN and the cathode CA, oxygen can be generated at the anode AN and hydrogen can be generated at the cathode CA.

Although not shown in FIG. 1, a pair of collector electrodes are provided at both ends of the stack including a plurality of electrochemical cells 10 for water electrolysis, and the terminals of the voltage applicator 50 are connected to the respective collector electrodes. may be connected. A pair of insulating sheets are provided on the outside of each of the collecting electrodes, and the stack is fastened together from the outside of these insulating sheets using a pair of end plates, bolts, nuts, and the like. The insulating sheet is made of a resin sheet or the like. Examples of materials for the resin sheet include glass epoxy resin, silicone rubber, PDM (ethylene propylene diene rubber), FKM (fluorinated rubber), and PTFE (polytetrafluoroethylene). , PP (polypropylene), PS (polystyrene), and the like.

A controller (not shown) controls the current amount of the voltage applicator 50, the flow rate of the anode fluid and the cathode fluid, the temperature of the electrochemical cell 10 for water electrolysis, and the like to desired values. Also, by connecting a plurality of stacks, it is possible to operate them in cooperation with a controller.

Furthermore, a water electrolysis system (not shown) may be constructed. In the water electrolysis system, for example, a pump for sending the anode fluid and the cathode fluid to the water electrolysis device 100, a gas-liquid separator for separating the electrolysis product gas and the liquid produced by the water electrolysis device 100, A dryer for recovering moisture and impurities, a compressor for compressing the electrolysis gas, a tank for storing the electrolysis gas, and the like may be provided.

Note that the effects of the water electrolysis device 100 of the present embodiment are the same as the effects of the electrochemical cell 10 for water electrolysis of the first embodiment, so the description thereof will be omitted.

The water electrolysis device 100 and the water electrolysis method of this example may be the same as those of the first embodiment except for the features described above.

(Second embodiment)
The electrochemical cell for water electrolysis 10 of the present embodiment is the same as the electrochemical cell for water electrolysis of the first embodiment except for the configuration of the face seal material 41 described below.

FIG. 3 is a diagram showing an example of the electrochemical cell for water electrolysis of the second embodiment.

The face seal material 41 has a three-layer structure in which elastic sheets 41B are provided on both main surfaces of a metal sheet 41A.

Examples of materials for the insulating elastic sheet 41B include silicone rubber, EPDM (ethylene propylene diene rubber), FKM (fluororubber), PTFE (polytetrafluoroethylene), PP (polypropylene), and PS (polystyrene). be able to. When the anode fluid is an aqueous solution containing alkali, it is appropriate to select an alkali-resistant material as the base material of the face seal material 41, and it is desirable to use EPDM, for example.

The metal sheet 41A is a member having higher rigidity than the elastic sheet 41B and is made of a corrosion-resistant material. Examples of such materials include titanium, stainless steel, and nickel. When the anode fluid is an aqueous solution containing alkali, it is appropriate to select an alkali-resistant material as the base material of the metal sheet 41A, and it is desirable to use nickel, for example.

Also, the metal sheet 41A may be plated with a dissimilar metal. For example, if the metal sheet 41A is made of stainless steel, the stainless steel sheet may be plated with nickel or a noble metal. note that. When the anode fluid is an aqueous solution containing alkali, it is appropriate to select an alkali-resistant material as the plating material, and it is desirable to use nickel, for example.

The sheet material forming the face seal material 41 may be fixed by an appropriate bonding method. This improves the ease of assembly of the electrochemical cell 10 for water electrolysis. Moreover, when the electrochemical cell 10 for water electrolysis is assembled, the electrolyte membrane 21 and the cathode power supply 25 are suppressed from being caught between the sheet members, and as a result, breakage of the sheet members can be suppressed. Examples of the bonding method include a method using an epoxy resin-based adhesive, and a vulcanization bonding method in which unvulcanized rubber and a metal sheet are vulcanized and bonded in a mold at the same time.

As described above, the electrochemical cell 10 for water electrolysis and the water electrolysis method of the present embodiment can improve the sealing performance of the face sealing material 41 for sealing the anode AN as compared with the conventional one.

Specifically, in the electrochemical cell 10 for water electrolysis of this aspect, the face seal material 41 has a three-layer structure including the metal sheet 41A and the elastic sheet 41B provided on both main surfaces of the metal sheet 41A. The rigidity of the face seal material 41 is improved as compared with the case where the face seal material 41 is composed of a single elastic sheet. As a result, in the electrochemical cell 10 for water electrolysis and the water electrolysis method of the present embodiment, for example, when the above members are fastened so as to press the face seal material 41 against the anode separator 26, the face seal material 41 is not uniform. Even if a strong fastening force acts, the face seal material 41 is prevented from falling into the first communication path 31A and the second communication path 31C. Therefore, in the electrochemical cell 10 for water electrolysis and the water electrolysis method of the present embodiment, compared with the case where the face seal material 41 is composed of a single elastic sheet, the face seal material 41 is deformed or damaged due to factors such as deformation or breakage. Since the possibility that the sealing performance of the sealing material 41 is deteriorated can be reduced, the anode fluid containing oxygen produced by electrolysis is less likely to leak to the outside.

The electrochemical cell 10 for water electrolysis and the water electrolysis method of the present embodiment may be the same as those of the first embodiment or the examples of the first embodiment except for the features described above.

The first embodiment, the example of the first embodiment, and the second embodiment may be combined with each other as long as they do not exclude each other.

Also, many modifications and other embodiments of the present disclosure will be apparent to those skilled in the art from the above description. Accordingly, the above description is to be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the disclosure. Details of its structure and/or function may be varied substantially without departing from the spirit of the disclosure.

An aspect of the present disclosure can be applied to an electrochemical cell for water electrolysis in which the sealing performance of a face seal material for sealing a cathode can be improved more than before.

10: Electrochemical cell for water electrolysis 21: Electrolyte membrane 22: Anode catalyst layer 23: Cathode catalyst layer 24: Anode feeder 25: Cathode feeder 26: Anode separator 27: Cathode separator 28: Insulating sheet 31: Anode flow channel 31A : First communication channel 31B : Electrode passage channel 31C : Second communication channel 32 : Cathode channel 32A : First communication channel 32B : Electrode passage channel 32C : Second communication channel 41 : Face sealing material 41A : Metal sheet 41B : Elastic sheet 42 : Face sealing material 42A : Metal sheet 42B : Elastic sheet 50 : Voltage applicator 100 : Water electrolyzer AN : Anode CA : Cathode

Claims (7)

an electrolyte membrane;
an anode provided on one main surface of the electrolyte membrane;
a cathode provided on the other main surface of the electrolyte membrane;
an anode separator provided on the anode and having a first channel through which an anode fluid flows;
a cathode separator provided on the cathode and having a second flow path through which a cathode fluid flows;
In an electrochemical cell for water electrolysis in which oxygen is generated at the anode and hydrogen is generated at the cathode by applying a voltage between the anode and the cathode,
a surface sealing material provided on the outer circumference of the region of the cathode-side main surface of the cathode separator facing the cathode;
The electrochemical cell for water electrolysis, wherein the face sealing material has a three-layer structure in which an elastic sheet is provided on each of both main surfaces of a metal sheet. a surface sealing material provided on the outer circumference of the region facing the anode of the main surface on the anode side of the anode separator,
2. The electrochemical cell for water electrolysis according to claim 1, wherein said face sealing material has a three-layer structure in which an elastic sheet is provided on each of both main surfaces of a metal sheet. 3. The electrochemical cell for water electrolysis according to claim 1, wherein said electrolyte membrane is an anion exchange membrane. 4. The electrochemical cell for water electrolysis according to claim 1, wherein said elastic sheet is resistant to alkali. The electrochemical cell for water electrolysis according to any one of claims 1 to 4, wherein the metal sheet is resistant to alkali. The electrochemical cell for water electrolysis according to any one of claims 1 to 5;
a voltage applicator that applies a voltage between the anode and the cathode;
A water electrolysis device comprising: an electrolyte membrane;
an anode provided on one main surface of the electrolyte membrane;
a cathode provided on the other main surface of the electrolyte membrane;
an anode separator provided on the anode and having a first channel through which an anode fluid flows;
a cathode separator provided on the cathode and having a second channel through which a cathode fluid flows;
a face sealing material provided on the outer periphery of the region facing the cathode of the cathode-side main surface of the cathode separator,
In the water electrolysis method for an electrochemical cell for water electrolysis, wherein the face seal material has a three-layer structure in which an elastic sheet is provided on each of both main surfaces of a metal sheet,
A water electrolysis method in which oxygen is generated at the anode and hydrogen is generated at the cathode by applying a voltage between the anode and the cathode.

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